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fix(zod): parser generation when content-type contains charset precision #3404

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fix(zod): parser generation when content-type contains charset precision #3404

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32b5647
fix(zod): parser generation when content-type contains charset precision
pierre-isabel-bbc May 20, 2026
328c784
fix(zod): parser generation when content-type contains charset precision
pierre-isabel-bbc May 20, 2026
59b4d3f
fix(zod): handle "exotic" json mime types
pierre-isabel-bbc May 20, 2026
431e3fc
fix: coderabbit suggestions
pierre-isabel-bbc May 20, 2026
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34 changes: 24 additions & 10 deletions packages/zod/src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1335,13 +1335,25 @@ const parseBodyAndResponse = ({
| OpenApiRequestBodyObject;

// Only handle JSON and form-data; other content types (e.g., application/octet-stream)
// are skipped - unclear if this is correct behavior for root-level binary/text bodies
const jsonMedia = resolvedRef.content?.['application/json'];
const formDataMedia = resolvedRef.content?.['multipart/form-data'];
const [contentType, mediaType] = jsonMedia
? (['application/json', jsonMedia] as const)
: formDataMedia
? (['multipart/form-data', formDataMedia] as const)
// are skipped - unclear if this is correct behavior for root-level binary/text bodies.
const contentEntries = Object.entries(resolvedRef.content ?? {});

const jsonContent = contentEntries.find(
isMediaType(
// application/json
// application/geo+json
// application/ld+json
// application/manifest+json
String.raw`^application\/([\w-]+\+)?json$`,
),
Comment on lines +1341 to +1348

@coderabbitai coderabbitai Bot May 21, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

JSON media-type matcher still misses valid vendor subtypes.

The current pattern rejects valid JSON media types like application/vnd.api+json (dot in subtype), so schema generation can still be skipped for legitimate responses/requests.

Suggested fix 
   const jsonContent = contentEntries.find(
     isMediaType(
       // application/json
       // application/geo+json
       // application/ld+json
       // application/manifest+json
-      String.raw`^application\/([\w-]+\+)?json$`,
+      // application/vnd.api+json (and other valid vendor subtypes)
+      String.raw`^application\/([^/;]+\+)?json$`,
     ),
   );
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/zod/src/index.ts` around lines 1341 - 1348, The media-type regex
used when computing jsonContent (contentEntries.find(... isMediaType(...)))
disallows dots in vendor subtype names (so types like application/vnd.api+json
are rejected); update the pattern passed to isMediaType (the
String.raw`^application\/([\w-]+\+)?json$` literal) to allow dots (and keep
existing word, plus and hyphen chars) in the subtype token (e.g. use a character
class that includes '.' such as [\w.-] or [\w.+-]) so vendor subtypes like
vnd.api+json are accepted.

);
const formDataContent = contentEntries.find(
isMediaType('multipart/form-data'),
);
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const [contentType, mediaType] = jsonContent
? (['application/json', jsonContent[1]] as const)
: formDataContent
? (['multipart/form-data', formDataContent[1]] as const)
: [undefined, undefined];

const schema = mediaType?.schema;
Expand All @@ -1352,7 +1364,6 @@ const parseBodyAndResponse = ({
isArray: false,
};
}

const encoding = mediaType.encoding;

const resolvedJsonSchema = dereference(schema, context);
Expand Down Expand Up @@ -1390,7 +1401,6 @@ const parseBodyAndResponse = ({
},
};
}

const effectiveSchema =
parseType === 'body'
? removeReadOnlyProperties(resolvedJsonSchema)
Expand Down Expand Up @@ -1420,6 +1430,11 @@ const parseBodyAndResponse = ({
};
};

const isMediaType =
(pattern: string) =>
([contentType]: [string, object]): boolean =>
new RegExp(pattern).test(contentType.split(';')[0].trim().toLowerCase());

const getSingleResponse = (
responses:
| Record<string, OpenApiResponseObject | OpenApiReferenceObject | undefined>
Expand All @@ -1431,7 +1446,6 @@ const getSingleResponse = (

return responses['200'] ?? responses['2XX'] ?? responses['2xx'];
};

/* eslint-enable @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-call */

export const parseParameters = ({
Expand Down
213 changes: 213 additions & 0 deletions packages/zod/src/zod.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -6273,6 +6273,219 @@ describe('generateZod (content type handling - parity with res-req-types.test.ts
})
})

`);
});

it('content type with charset precision: comprehensive content type handling', async () => {
// Matches type gen test structure in res-req-types.test.ts
const schema = {
pathRoute: '/upload-form',
context: {
spec: {
paths: {
'/upload-form': {
post: {
operationId: 'uploadForm',
requestBody: {
required: true,
content: {
'multipart/form-data; charset=utf-8': {
schema: {
type: 'object',
properties: {
encBinary: { type: 'string' },
encText: { type: 'string' },
cmtBinary: {
type: 'string',
contentMediaType: 'image/png',
},
cmtText: {
type: 'string',
contentMediaType: 'application/xml',
},
encOverride: {
type: 'string',
contentMediaType: 'image/png',
},
formatBinary: { type: 'string', format: 'binary' },
base64Field: {
type: 'string',
contentMediaType: 'image/png',
contentEncoding: 'base64',
},
metadata: {
type: 'object',
properties: { name: { type: 'string' } },
},
},
required: [
'encBinary',
'encText',
'cmtBinary',
'cmtText',
'encOverride',
'formatBinary',
'base64Field',
'metadata',
],
},
encoding: {
encBinary: { contentType: 'image/png' },
encText: { contentType: 'text/plain' },
encOverride: { contentType: 'text/csv' },
metadata: { contentType: 'application/json' },
},
},
},
},
responses: {
'200': {
content: {
'application/json; charset=utf-8': {
schema: {
type: 'object',
properties: {
success: { type: 'boolean' },
uploaded: { type: 'number' },
},
},
},
},
},
},
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},
},
},
},
output: { override: { zod: { generateEachHttpStatus: false } } },
},
} as unknown as GeneratorOptions;
const result = await generateZod(
{
pathRoute: '/upload-form',
verb: 'post',
operationName: 'uploadForm',
override: {
...zodOverride,
zod: {
...zodOverride.zod,
generate: { ...zodOverride.zod.generate, response: true },
},
},
} as unknown as Parameters<typeof generateZod>[0],
schema,
testOutput,
);
// encBinary: encoding image/png → File
// encText: encoding text/plain → File | string
// cmtBinary: contentMediaType image/png → File
// cmtText: contentMediaType application/xml → File | string
// encOverride: encoding text/csv overrides contentMediaType image/png → File | string
// formatBinary: format: binary → File (same as instanceof check)
// base64Field: contentEncoding base64 → stays string
// metadata: object → object schema
expect(result.implementation)
.toBe(`export const UploadFormBody = zod.object({
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"encBinary": zod.instanceof(File),
"encText": zod.instanceof(File).or(zod.string()),
"cmtBinary": zod.instanceof(File),
"cmtText": zod.instanceof(File).or(zod.string()),
"encOverride": zod.instanceof(File).or(zod.string()),
"formatBinary": zod.instanceof(File),
"base64Field": zod.string(),
"metadata": zod.object({
"name": zod.string().optional()
})
})

export const UploadFormResponse = zod.object({
"success": zod.boolean().optional(),
"uploaded": zod.number().optional()
})

`);
});

it('json exotic content type: comprehensive content type handling', async () => {
const schema = {
pathRoute: '/upload-form',
context: {
spec: {
paths: {
'/upload-form': {
post: {
operationId: 'uploadForm',
requestBody: {
required: true,
content: {
'application/geo+json': {
schema: {
type: 'object',
properties: {
success: { type: 'boolean' },
uploaded: { type: 'number' },
},
},
},
},
},
responses: {
'200': {
content: {
'application/manifest+json': {
schema: {
type: 'object',
properties: {
success: { type: 'boolean' },
uploaded: { type: 'number' },
},
},
},
},
},
},
},
},
},
},
output: { override: { zod: { generateEachHttpStatus: false } } },
},
} as unknown as GeneratorOptions;
const result = await generateZod(
{
pathRoute: '/upload-form',
verb: 'post',
operationName: 'uploadForm',
override: {
...zodOverride,
zod: {
...zodOverride.zod,
generate: { ...zodOverride.zod.generate, response: true },
},
},
} as unknown as Parameters<typeof generateZod>[0],
schema,
testOutput,
);
// encBinary: encoding image/png → File
// encText: encoding text/plain → File | string
// cmtBinary: contentMediaType image/png → File
// cmtText: contentMediaType application/xml → File | string
// encOverride: encoding text/csv overrides contentMediaType image/png → File | string
// formatBinary: format: binary → File (same as instanceof check)
// base64Field: contentEncoding base64 → stays string
// metadata: object → object schema
expect(result.implementation)
.toBe(`export const UploadFormBody = zod.object({
"success": zod.boolean().optional(),
"uploaded": zod.number().optional()
})

export const UploadFormResponse = zod.object({
"success": zod.boolean().optional(),
"uploaded": zod.number().optional()
})

`);
});
});
Expand Down
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